Bearing



Oct. 26, 1954 r P. l. J. GERARD BEARING 7 Sheets-Sheet 1 Filed July 17, 1952 rroR/veys Oct. 26, 1954 P. L: J. GERARD 2,692,803

BEARING Filed July 17, 1952 '7 sheets-sheet 2 H TTOWMl-:ys

Oct.. 26, 1954 P. L J. GERARD 2,692,803

BEARING Filed July 17%1952 "/'sneets-sheet 4 Hr'ToR msys Oct. 26, 1954 P. l. J. GERARD 2,692,803

' BEARING Filed July 17, 1952 7 Sheets-Sheet 5 Oct. 26, 1954 P. L. J. GERARD 2,692,803.

' BEARING Filed July 17. 1952 l 7 Sheets-Sheet 7 Pri-0R Ive/vs PatentedA Oct. 26, 1954l tot Societe dEtude `et @Exploitation-dlr*Palier Fluide "(S; En E. P.- F.), Lyon, 'RhonafFranoe,

aicompany of France fApplicationJuly 17, 1952,. Serial No. 299,354 vv'Claims priority, application-Franceduly? 31,` 1951 18 Claims.

The present inventionzconcerns bearings of fthe ItypeJin which an annular olearancefis 'formed between. two concentricmembers, one-of which is adapted to turn'inwrelation to theother and in` whichvmeans `are.` provided Iforizfeeding huid under pressure to the said; `elearancerso that the .two concentric; members. cani never come 4into contact with one` another.

In :the knownbearingsaofnthis type,Y when `.the

rotative. member is,displaced.=;withrespect to the otherfmember .under `the action of external loads, the equilibrium off thepressuresfiis-Lmodied by reason offthe said displacementywhich produces :tails `disadvantages 1insome leases,

The presentlzinvention has eior its `object `to :provide a bearing whichisfof Athe aforesaid type, but in which, despite 4the external -xloads applied tothe rotative member, the latterremainscompletelyfconcentric tothe other'member, Awhile 'the pressure conditions vof the fluid are modified as a Afunction `ofthe external `loads acting ons the Irotative mem-ber. .i According to the invention;:theaforesaidebearing is .combinedwith at'least'one movable member situated in the circuit ofthe fluid underpressure, but. outside the `assembly formed. bylthe aforesaid two `concentric members, thesaid mov- `able elementbeing.` soA arranged "that, hwhen the external loads are exerted onthe rotative member, the movable element in question takes up a positiondetermined bythe said 'loads and 4.thus Acreates pressure conditionsdiierentfrom those Aexisting in 'the absence of 'the aforesaid external loads, `so that fresh pressure conditions, .corresponding to the new loads, are 'created without lthe rotative member having to take up al position different fromthat'whi'chit occupies in the absence of such externalloads, "the said member being able,"notably, to remain completely `concentric-to the `other member.

AIt-mustbe understood that the-invention is r-applicable ltoranyconcentric members, `one of which is intendedto turn-inrelation'tothe other. there will bei described in the following, the lcase oil a shaft turning in= a' fixed bearing, Y but it will vbienu understood that #the samefconditions arise .in fthe :case fofwa :pivot fabout l whieha-concentric member:surroun'ding'l` it turns.

ltrmust :also be. understoodsthat :fthe invention isninmo wayV limited to.,-afwselffcentering inra plane and `that icthis `self-centering.-r may take l place either fin a single plane, inztwosperpendiouwlarplanesfin ft-hreegdirections at,l20.ap,art and In the. accompanying drawings: i i-E'igs.; l, `and Zware-'diagrammaticillustrations ot 4the invention under conditions 1 in which Yself-- centering y0i? 7,theLpistonl takes lplaoe, `and Figs-S-lZ show Aa number rof embodiments ofthe invention as appliedto abearinginwhich arotative shaft is mounted. i

In :order thatthe inventionmaybe more readily understood, :referencewwillurst be .made to Figures lvand 2,-in-which theconditioins under `which `the `self-centering according, tot the linvention takessplace are `diagrammatically.illustrated. l

In Figure `l, there :to Y. bei;constantly. maintained i in the same kposition Yin relation to a cylinder b regardless ofthe efforts exerted on the-:saidpiston in the axial direction, runder the eiiectiof pressure conditionscreated on either side of the said piston with the aid of a .movableelement o, the position of which is `varied in accordance ,withthe `eiiorts exerted on the piston afwhile the latter must not change its position in order'to vary the pressure condi- `tionswhenthe eiiorts exertedthereon change.

AThe liquidfin the.illustrated-.example is situatedin a reservoir d, a pump e feeding' the `said liquid under pressure into a distributor body" f inivhich thereslides a slide valve c which forms 'the aforesaid movable element. 1Ducts gl 4and `g2 .feed vthe two ends of the `cylinder-Min which the piston "a ssituated. Inl addition, `the ends ofthe distributorf areconnected by' ducts jili2 to auxiliary chambers nl andn`2 formed inthe ends of thecylinder b and in `wlfiichthere engage axial extensionsfy'l and 72 respectively 'of `the piston` a; the said extensionsbeingA oi smaller diameter. 'Thev discharge from"'the saidends towards the reservoir `takes 'place through ducts kl and 'k2 "respectively, f which communicate through aduct h withthe reservoird. ne slide valve chas acentral'annular groove m to which liquid-under pressure is constantly red from the pump e`, and "calibrated constrictions Zi, 'Z2 throughwhich the' ducts z'i,"i2 are red. Two othergrooves `tl and Lt2 are formed inthe slide `valve'on` eitherside ofthe groove m. These two 4 grooves-communicate with the" discharge ducts isshown .a piston a intended sary pressure is maintained .in the auxiliary chambers nl andnZ through the constricted orices ll and Z2 respectively, the fluid flowing from the said chambers through the ducts kl and k2. In the position of equilibrium, the cross-sectional areas of throughflow of the ducts Icl and k2 are equal and consequently the pressures in the auxiliary chambers nl and 11,2 are exactly equal.

When a forceis exerted in the direction vof the axis on the piston a, for example from left to right, the area of throughfiow of the duct ici is reduced, while that of the duct kl is increased, so that the pressure in they auxiliary chamber ni formed in the cylinder opposite the extension il falls and the pressure in the auxiliary chamber 11.2 opposite the extension i2 rises.

Owing to the presence of the two constrictions Zi,V Z2 in the slide valve c, the pressure obtaining to the right of the vlatter becomes greater than that obtaining to the left, so that the slide valve c is moved from right to left. This movement of the slide valve connects 'the duct g2 feeding the main chamber p2 with the admission and connects the duct gl feeding the main chamber pl with the discharge. The piston is therefore brought into the central position against the action of the load and the pressure difference between the two sides of the piston tends to maintain it in this position. l

`To sum up, the variations of the load produce a permanent displacement ofthe slide valve instead of producing a permanent displacemnt of the shaft, which only undergoes temporary displacements which are automatically cancelled out by movements of the slide valve.

rThe diagram of Figure 1 corresponds to a bearing in which no discharge groove is situated between the pressure zones, this bearing being of the type in which the pump delivers only when the shaft is subjected to asymmetrical external forces. Y

The example of Figure 2 is a diagram of the principle of the invention as applied to a fluid bearing of the type described in the patent applications filed in the United States, on the one hand in the name of Mr. Paul Grard on September 24, 1946, Serial No. 699,051 (abandoned, but see continuation-in-part, Patent No. 2,660,485, Nov. 24, 1953), for Improvements in Hydraulic Supports and, on the other hand, in the names `of the company entitled Gendron Frires (assignee)V and Mr. Paul Grard on July 8, 1950, Serial No. 172,666, Patent No. 2,660,484, November 24, 1953, for Improvementsin Bearings, in which longitudinal discharge grooves are formed between the pressure zones. In this diagram, the said grooves are represented by discharge ducts hl and h2. The ducts gl and y2 are always connected to the admission, the pump e constantly feeding into the bearing in order to compensate for the losses through the grooves representedv by the ducts hl and h2. When the slide valve is in the central position, the ducts gl andy? have an opening `section equal to half their total section. Simithe piston a itself directly `controls-.the continuous discharge of the fluid under pressure from the pressure zones. In fact, when `the piston a moves from left to right, as assumed in the previous case, under the action of the external loads, the said piston a reduces the discharge section of h2 and increases the discharge section of hl, Consequently, even before the movement of the slide valve has produced a pressure increase inthe chamber p2 and a corresponding pressure reduction in the chamber pl, a pressure increase occurs in the chamber p2 and a pressure reduction occurs in the chamber pl, whereby the amplitude of the initial displacement of the pisvton a is reduced. Furthermore, on return Vof the piston a to its position of equilibrium under the action of the increase in the delivery through gli and of the corresponding reduction in the delivery through gl (resulting-from the change of position of the slide valve c) the reduction of the discharge section of hl and the increase of that of h2 produces a damping effect which prevents the piston a from Vibrating substantially.

Figures 3 to 12 show a number of embodiments of the invention as applied to a bearing in which a rotative shaft is mounted.

` There is shown in horizontal section in Figure 3 one of the bearings in which there is mounted a shaft supporting a grinding wheel, the said bearing comprising means for self-centering action in a single plane.

Figure 4 shows the same bearing in vertical axial section, as well as in two-transverse sections, this illustration being intended to enable the idea of the invention to be more clearly seen.

Figure 5 -is a View similar to that of Figure 4 and shows a bearing according to the invention which effects self-centering in one plane, but in the case where the position of the shaft in the bearing is controlled by a templet during operation, as described in the U. S. patent application filed on July 8, 1950,Serial N o. 172,66*?,Patent No. 2,663,977, December 29, 1953,in the names of the company entitled Gendron Frres (assignee) and Mr. Paul Grard, for System for Controlling the Position of a Shaft in its Bearings.

Figurev dis-av View in axial section of a bearing according to the invention in which the selfcentering is effected in two perpendicular planes.

Figures 7 and 8 are transverse sections along planes extending along the lines'l--L 8 8 of Figure 6, respectively, and

Figure 9 is a partial perspective View of an element of the bearing according to Figure 6.

Figure 10 shows, similarly to Figures 4 and 5, a bearing according to the invention in which the self-centreing is effected in three radial directions apart. p

Figure 11 is a plan view of the control element ofthis assembly, and

Figure 12 shows a simplified ccnstructional form.

Y Referring rst of all to Figures 3 and 4, there will be seen at l a shaft on which a grinding wheel 2 is mounted. There will be seen at 3 one of the bearings of the said shaft, the said bearing being arranged in accordance with the invention. The said bearing comprises four main chambers ll fed with fluid under pressure. The two chambers which effect the stabilization in the vertical plane are fed through a normal pipe 5, the other two chambers being fedthrough ducts 6, the opening section of which is controlled by a movable element 'l disposed in the feed circuit and consisting, in the illustrated example, of a slide valve adapted to move axially in a distributionmemberA 8. 'The said distributor'is constantly fed from the pump 9 through a duct l0. In the position of equilibrium,ithe opening sections of the two ducts 6 are the same owing tothe fact `that the slide valve is in the central position and exactlycovers one half of the section Vof the said ducts. The fluid under pressure is..discharged through longitudinal grooves Il which communicate with the reservoir `I2 through a duct' `I3. The discharge. through the grooves ll,\which is `controlled inthe diagrammatic illustration of Figure 2 by the axial movements of the piston a in relation to the ducts hl and h2,-is in fact controlled by the radial movements `of the shaft. described, apart from the additional feed through the'slide valve, is similar to that described inthe aforesaid patent application, metal-to-metal contact betweenthe shaft and the bearing being prevented by continuous circulation of the fluid under pressure through the bearing.

yAccording to the invention, in order to-ensure self-centering of the shaft, the bearing 3 is completed by an auxiliary device axially offset in relation to the actual bearing hereinbefore described. It is particularly j proposed, as illustrated, to situate the said auxiliary device near the end of the shaft which is likely to be subjected to irregular external forces (in the presentcase the end on which the grinding wheel is mounted). The said additional device comprises, in the example of Figures 3 and 4, two auxiliary or 4reference chambers i4 to which fluid under pressure is fed through ducts l5 leading to the ends of the distributor member in which the slide valve 1 ismounteol. Theclucts I5 are fed with fluid under pressure which enters the `distribution member through the duct by way of calibrated constrictions I6. The discharge of the fluid under pressure takes place through longitudinal grooves lI disposed in alignment with the longitudinal grooves ll and communieating with the latter. On comparison of the self-centering bearing illustrated in Figures 3 and 4 with the diagram of Figure 2, it will be seen that the slide valve is identical with that illustrated at c in Figure 2, that the ducts 6 feedingthe main chamber l correspond to the ducts gland g2 feeding the main chambers pl and p2, that ther longitudinal grooves ll correspond to the discharge ducts hl and h2, the discharge ducts l1 correspond to the discharge clucts kl and k2, and finally that the feed ducts l'5 of the auxiliary chambers l4correspond to the ducts il and i2 feeding the auxiliary chambers nl and n2. When the grinding wheel 2 is subjected to a force rin-a horizontal plane, the shaft tends to undergo in this plane a certain movement in relation to the axis of the bearing, which displacement acts immediately in the zone occupied by the auxiliary device and brings about a reduction in the discharge section in the zone in which the shaft is moved towards the inner supporting surface, while on the other hand the pressure is reduced in the opposite zone owing to the increase in the sectionof the discharge ducts. The pressure in that end of the distributor member 8 which is connected to the chamber in which the said pressure is thus increased andthe slide valve 1 -is accordingly moved. This movement if the slide vva'lyve .produces `antincrease in the feed section of the main:.:chamber The bearing hereinbefore dii-"situated in theffzonerftowards :which ther shaft tends-'to lmovefand ia corresponding reduction in the diametrally opposite Zone. Thus, thehshaft is prevented from moving out of alignment or is immediatelyyreturned into the `concentric axial position. The pressure conditions corresponding to the new-conditions are therefore createdfs'olely byl :the new` `position v-occupied lby L the slide valve without fthe shaft having to change its position.

TFigure' I'showsintheisame manner `as Figure 4 a self-centering bearing according `tothe invention Aas iapplied toa grinding machine `'in which thelshaft isintended `to take up 'predetermined positions underfthe controlof templet in the cou-rse of the grinding Work. Such a machine has Ibeen fdescribed in ftheeaforesaid patent application. In this A case; the -obj ect of the i present invention is to `prevent the-shaft `from leaving y theecc'entric position `determined `by the templet. The said bearing is similar in its broad outlineto that described-inFiguresS and 4, with the rdifference that the-'slideV-valve la which controls thelpressure conditions in the A bearing by its `position fin :the imember, `has no constricted'passages' for `feeding :the ducts yI5 communicating with the auxiliary chambers lil. Infact, I'the said Ychambers-are fedibyi a duct 1`l8 through the ldistributor` 18a; the movable- `element l s-of which movesvalongthe templet l2l). The pressu-resobtaining` 'inthe chambers vllt/are simplytransmitted -`through the-said `ducts Al 5 i to the-ends of thememberrsofas `toV bring the slide valve 'la intovthe position# determined by' the `pressure conditions created in each positionbf the shaft in fthe-bearings.

*In ithe two y"examples Lhereinbefore described, the bearing is `self-centering only'inthe horizontal plane, i this case corresponding `to grinding bya wheelJacting in the `said plane.

'l-Iowevenun Iother i applications, it is desirable to effect a-2s"elf-c'ente'ring'in` all directions `In the-example:lillustrated in` Figures 6 to' 9; this self-centering inall'directionsis effected `in two perpendicular `fplanes. In'thisiexample, the main chambershll 'and fthe :auxiliary chambers I4 Hare fedllfrom ducts 2l -througha :chamber 22,?this chamber communicating ltl'lroughducts 23 with theffm'ain chambersf lyandf-through constricted ducts 22'4- with Ythe.auxiliary-chambers I4. The controlof .the feed-of Sthe main chambers by vthe pressure yconditions. obtainingwin the auxiliary chambers requires, Fior-teach fof `theplanes in which thel-self-centering is ttoibe effected, at least one Vexternal lmovable element acting 4in theimanner offlthe slide valve c ofFigure In the 'illustrated example, the `control in each of the lsaid planes isfeffectedlby two pistonsk25 mountedon a ring concentric with `the bearing at two `diametrically oppositepoints of the said ring,so` that any movement of oneof the said pistons is accompaniedby a movement in the opposite direction and of equalamplitude of the other piston, whereby a reduction in the section of one 'of the passages 23 and an increase in the sectionof the diametrically opposite passage 23 are simultaneously produced in the same degree. The tworings, on each of Awhich two` pistons 25 are mounted as hereinbefore described, are in turnmounted on a universal joint on the bearing 29, thediameters on which the twopairs offpistons `are mounted being perpendicular to one another. Each of the. pistons 25` slides ina cylindrical` bore?` 28; l the.; pressure fin said'rbore'. thus actingzon. the .fronafacenzof fthe` .saidspiston. t'Ihe chambers I4 themselves are spaced at 90around` the periphery of the bearing and their relative positions correspond to those of the main chambers 4.

In this example, it will be seen that the movable element c of Figure 2 may be replaced by a plurality of movable elements (four in the illustrated example) which are suitably associated and may be incorporated in the structure of the bearing, whereby a construction in the form of a single unit can be obtained.

The operation of the bearing described in this example is the same as before, except that each assembly of two; auxiliary chambers I4 diametrically opposite one another acts in one of the two orthogonal planes, the combination of the actions in these two planes permitting of automatically compensating for the external forces exerted on the shaft in any direction whatever,

In the example illustrated in Figures and ll, the number of movable elements which control the pressure conditions in the bearing is 3, these movable elementsnot consisting of slide valves in this example, but of an assembly of three diaphragms and a circular plate, the position of which controls the feed of the main chambers of the bearing. The said plate normally occupies a symmetrical position in relation to the apertures through which the fluid under pressure is introduced into the chambers of the main bearing, but takes up an inclined position when the pressure conditions in the auxiliary chambers change.

This pressure acts on the plate through diaphragms 3| in which the respective pressures of the said auxiliary chambers obtain. In the example illustrated in Figures 10 and 1l, the automatic balancing is effected in three planes 120 apart. The main bearing also comprises three main chambers 4, 120 apart, and the auxiliary device comprises three corresponding chambers i4. The chambers It each communicate with one of the diaphragms 3 I. The fluid under pressure is fed into the pump in a casing 32 in which there is disposed a plate 33 urged by a spring 34 against a pivot 35. The pipes 3S feed the main chambers 4 of the bearing communicating with passages 31 disposed perpendicularly to the plate when the latter occupies its normal position in the absence of asymmetrical pressures, the said plate being adapted to throttle to a varying degree one or two of the passages while further freeing the others, or the other, when it takes up an inclined position. The said plate is in turn controlled by the diaphragms 3|, which comprise hooks 38 provided with points 39 which bear against the lower face of the plate. The auxiliary chambers I4 are fed through the diaphragms 3l, in which a constricted passage 4|] is provided for this purpose.

Figure 12 shows a simplified constructional form in which only one auxiliary chamber I4 is provided, the pressure which obtains in this chamber acting on a slide valve 7, the other iace vof which is subjected to an antagonistic pressure provided by the feed pump, but acting on a smaller surface. Owing to the fact that the pump feeds, on the one hand, directly, the chamber' l2 in which this antagonistic pressure acts, and on the other hand, through a constriction, the auxiliary chamber, the slide valve is only in equilibrium when the discharge section of the auxiliary chamber bears a predetermined ratio to the section of the aforesaid constriction.

What is claimed is:

l. A bearing .structure comprising two substantially concentric intertting members with a clearance therebetween, one member being stationary and the other rotatable, a plurality of pressure zones equally spaced around the periphery of said stationary member, means to feed iiuid under pressure to said pressure zones, at least two reference chambers formed in the periphery of said stationary member, outside said pressure zones, means to feed uid Linder pressure to said reference chambers and a distributor connected to said reference chambers, having movable control means responsive to the pressure in said reference chambers, and controlling the feed circuit of said pressure zones, whereby any unbalance between the pressures in said reference chambers clue to load variations determines a change in the position of said movable control means until a new position of equilibrium determined by the new position oi said movable control means is reached, without change of the relative position of the axes of said stationary and rotatable members.

A bearing structure comprising two substantially concentric interntting members with a clearance therebetween, one member being stationary and the other rotatable, a plurality of pressure zones equally spaced around the periphery of said stationary member, means to feed said pressure zones with iiuid under pressure, longitudinal discharge grooves formed between said zones, at least two reference chambers formed in the periphery of said stationary inembers, outside said pressure zones, means 4to feed fluid under pressure to said reference chambers and a distributor connected to said reference chambers, having movable control means responsive to the pressure in said reference chambers, and controlling the feed circuit of said pressure zones, whereby any unbalance between the pressures in said reference chambers due to load variations determines a change in the position of said movable control means until a new position oi equilibrium determined by the new position of said movable control means is reached, without change of the relative position of the axes of said stationary and rotatable members, while said rotatable member furthermore directly controls the continuous discharge oi the fluid under pressure through said longitudinal grooves thereby reducing its initial displacement and creating a damping effect opposing vibrations.

3. A bearing structure according to claim l in which said rotatable member is constituted by a shaft and said stationary member by at least one bearing.

4. A bearing structure according to claim 2 in which said rotatable member is constituted by a shaft and said stationary member by at least one bearing.

5. A bearing structure according to claim 2, in which the rotatable member is constituted by a shaft on which a grinding wheel is mounted, said stationary member being constituted by at least one bearing, means being provided for control-` ling the position of the axis of said shaft from a templet.

6. A bearing structure according to claim 1,y in which two diametrically opposed reference chambers are provided and in which said distributor control means comprises a sliding movable member.

'7. A bearing structure according to claim 2, in which two diametrically opposed reference chambers are provided and in which said distributor control means comprises a sliding movable member.

8. A bearing structure according to claim 1, in which four reference chambers are provided 90 apart around the axis of said stationary member, whereby automatic control of the position of said rotatable member is effected in two orthogonal planes.

9. A bearing structure according to claim 8, in which the distributor control means comprises a movable member for each reference chamber in the form. of a piston sliding in a cylindrical bore communicating directly with said reference chamber, means being provided to mechanically connect diametrically opposed pistons of each pair, so that any movement of one of said pistons is accompanied by a movement in opposite direction and of same amplitude of the other, each pair of pistons thus performing the same function as a single slide valve, controlled by the pressures in two diametrically opposed reference chambers.

l0. A bearing structure according to claim 2, in which four reference chambers are provided 90 apart around the aXis of said stationary member, whereby automatic control of the position of said rotatable member is effected in two orthogonal planes.

ll. A bearing structure according to claim 10, in which the distributor control means comprises a movable member for each reference chamber in the form of a piston sliding in a cylindrical bore communicating directly with said reference chamber, means being provided to mechanically connect diametrically opposed pistons of each pair, so that any movement of one of said pistons is accompanied by a movement in opposite direction and of same amplitude of the other, each pair of pistons thus performing the same function as a single slide valve, controlled by `the pressures in two diametrically opposed reference chambers.

12. A bearing structure according to claim 1, in which automatic control of the rotatable member position is effected in n radial directions, n being a whole number equal at least to 3, and in which there are provided u reference chambers spaced 360/n apart around the periphery of said stationary member.

13. A bearing structure according to claim l2, in which the distributor control means comprises a swivellably mounted circular plate and an assembly of n diaphragms, through which the pressure in the n reference chambers acts on said plate, the position of which controls the feed of said pressure zones.

14. A bearing structure according to claim 2, in which automatic control of the rotatable member position is effected in n radial directions, n being a whole number equal at least to 3, and in which there are provided n reference chambers spaced 360/n apart around the periphery of said stationary member.

15. A bearing structure according to claim 14, in which the distributor control means comprises a swivellably mounted circular plate and an assembly of n diaphragme, through which the pressure in the n reference chambers acts on said plate, the position of which controls the feed of said pressure zones.

16. A bearing structure comprising two substantially concentric interi'itting members with a clearance therebetween, one member being stationary and the other rotatable, a plurality of pressure Zones equally spaced around the periphery of said stationary member, means including a pump to feed fluid under pressure to said pressure zones, a reference chamber formed in the periphery of said stationary member outside said pressure zones, means to feed fluid under pressure to said reference chamber and a distributor connected to said reference chamber, said distributor having a movable member submitted to the presure in said reference chamber at one side and to a predetermined constant pressure on the other side, said distributor controlling the feed circuit in said pressure zones, whereby any unbalance creating pressure variations in said reference chamber due to load variations determines a displacement of said movable member until a new position of equilibrium deterfmined by the new position of said movable member is reached, without change of the relative position of the axes of said stationary and rotatable members.

17. A bearing structure according to claim 16, in which said movable member of said distributor is constituted by a slide valve, one face of which is submitted to the pressure of said reference chamber and the other, of a smaller crosssection, to the counteracting constant pressure fed by the pump feeding said pressure zones, said feed pressure being furthermore fed through a restricted passage to the face of said slide valve submitted to the pressure in said reference chamber.

18. A bearing structure comprising two substantially concentric interfitting members with a clearance therebetween, one member being stationary and the other rotatable, a plurality of pressure Zones equally spaced around the periphery of said stationary member, means to feed said pressure zones with fluid under pressure, longitudinal discharge grooves formed between said zones, a reference chamber formed in the periphery of said stationary member outside said pressure zones, means to feed fluid under pressure to said reference chamber and a distributor connected to said reference chamber, said distributor having a movable member submitted to the pressure in said reference chamber at one side and to a predetermined constant pressure on the other side, said distributor controlling `the feed circuit in said pressure zones, whereby :any unibalance creating pressure variation in said reference chambers due to load variations determines a displacement of said movable member until a new position of equilibrium determined by the new position of said movable member is reached, without change of the relative position of the axes of said stationary and rotatable members, while said rotatable member furthermore directly controls the continuous discharge of the fluid under pressure through said longitudinal grooves thereby reducing its initial displacement and creating a damping effect opposing vibrations.

References Cited in the iile of this patent UNITED STATES PATENTS Number Name Date 2,062,250 Moller Nov. 24, 1936 2,354,296 Arms July 25, 1944 2,459,826 Martellotti Jan. 25, 1949 

